Wisconsin wireless provider Cellcom has confirmed a major cyberattack hit its systems. This attack is responsible for the widespread service outage starting May 14, 2025. The incident severely disrupted voice and SMS services for many Cellcom customers. Affected subscribers were across Wisconsin and also in parts of Upper Michigan. They were unable to make regular phone calls or send any text messages. Today Cellcom CEO Brighid Riordan officially confirmed what many had already suspected. She stated the company indeed suffered a malicious cyberattack not just a technical issue. Riordan acknowledged this situation was unfortunate but said Cellcom was not unprepared for it.
The Cellcom CEO said they have protocols and plans for exactly this situation. From the very start of the incident Cellcom followed these established internal plans. This response included engaging outside cybersecurity experts to assist with the ongoing recovery. They also promptly notified the FBI and relevant Wisconsin state government officials. Cellcom teams are now working around the clock to bring systems safely back online. The incident was reportedly concentrated on an area of their network quite separate. This area is away from where Cellcom stores sensitive customer information and data. Cellcom has stated there is no evidence that any personal information was impacted. This includes customer names addresses or any of their private financial information.
Initially Cellcom had claimed the widespread disruption was caused by a technical issue.
The company stated that data services and some messaging apps remained operational. These included iMessage and also the RCS messaging services for many affected users. Importantly Cellcom said that 911 emergency services were also unaffected by the outage. However Cellcom users became increasingly frustrated by the prolonged loss of their service. Many were also unable to port their phone numbers to other carriers. This inability to port was due to Cellcom’s own service platforms having issues. The lack of clear communication initially also added to widespread customer frustration.
On May 19 Cellcom successfully began bringing some of its affected services back online. This partial restoration included SMS text messaging for many of its waiting subscribers. Making and receiving phone calls to other Cellcom subscribers also started to resume. However the company says they cannot promise when full services will be restored. They are unable to share exact recovery milestones with any complete confidence at present. Cellcom’s team continues to build on progress made and aims for full restoration soon. Their best current estimate is that full service will return by this week’s end. Cellcom advises subscribers with issues to toggle airplane mode or restart their phones. The CEO also shared a video message explaining the situation and ongoing recovery efforts.
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